The present invention relates generally to probes for monitoring the condition of a fetus and/or the in utero environment, and more specifically to fetal probes having improved visual monitoring.
During in utero labor and delivery of a fetus, fetal probes are used to monitor the health of the fetus. Fetal probes having pulse oximeters are typically used to measure various blood characteristics including arterial blood oxygen saturation and pulse rate. Pulse oximetry sensors pass light through a portion of the fetus"" skin and photo-electrically detect pulsatile changes in the absorption of the light by the tissue. The detected light is then used to determine the characteristic of interest.
In order to achieve accurate measurements, the aforementioned sensing devices must maintain contact with the fetus at an appropriate part of the fetus"" body. The quality of the optical signal generated by the pulse oximeter sensor depends, in part, on the placement of the sensors on the fetus"" body and on the quality of optical coupling between the sensor and the patient. The quality of optical coupling is related to the amount of light emitted by the sensor that actually enters the fetus"" tissue and to the portion of the light received by the sensor that actually passes through the fetus"" blood-perfused tissue.
Tissue characteristics at the sensor site can affect the quality of the optical coupling between the sensor and the patient. The presence of hair or vernix on the skin will attenuate the light transmitted into the tissue by the sensor. For example, if the sensor is placed over dense hair, the system may not be able to appropriately process the signal. Consequently, it is important that the physician position and orient the fetal probe at a proper place on the fetus.
One method of placing the fetal probe adjacent the fetus is through manual assessment of the womb to determine the orientation of the head of the fetus and depth of the fetus within the womb. Once the physician has determined the position of the fetus, the physician picks a line of entry and introduces the fetal probe along the line to try to place the fetal sensors on the fetus"" cheek. Unfortunately, the physician will only have tactile feedback in regards to the positioning of the sensors and will have no visual indication of the position of the fetal sensors relative to the fetus. If the physician has misassessed the position of the fetus and has not placed the fetal probe adjacent the fetus"" cheek, the physician will have a difficult time in correctly positioning the fetal probe.
Accordingly, what is needed are systems and methods that allow the user to monitor the location at which the fetal sensor was, is, or will be placed within the womb.
The present invention generally provides improved systems and methods for improved visual monitoring of a fetus in utero. In particular, the present invention provides improved methods and systems of improved visual monitoring of the placement of fetal sensors in utero. The probes of the present invention generally include an optical imaging assembly, and a spacing mechanism that creates a space between the imaging assembly and the fetus so as to provide a wide field of view for the imaging assembly.
The fetal probes of the present invention will generally include an imaging device, such as an optical fiber bundle, an optical conduit, CCD camera, or the like. The imaging device can be coupled to a distal housing of the fetal probe to visually image and/or illuminate the same or nearby region of the in utero environment or fetus that is adjacent the distal housing. The images from the illuminated portion of tissue are transmitted through the imaging device to an optical viewing device such as a hand-held image viewing instrument, camera, or a video monitor.
In some exemplary embodiments, the fetal probe will include fetal oximetry sensors that have a light emitter (e.g., an LED) and a light detecting sensor. The light emitter can emit an infrared light, a visible light, or the like. The imaging device can be positioned adjacent the fetal oximetry sensors so as to provide a visual indication of the position of the fetal sensors relative to the fetus"" tissue.
In some arrangements, the light emitter can be used for multiple purposes, such as for both spectral pulse oximetry and for illuminating the fetus"" tissue for visual examination. Alternatively, a separate illumination source (e.g., such as an optical fiber coupled to a broad spectrum light source) can be used to provide illumination for the visualization of the region of the fetus.
The light detecting sensors can be configured to sense the light emitted from the light emitter for pulse oximetry purposes. However, in some arrangements, the light detecting sensors can also be configured to detect the light for visualization purposes. For example, a light sensor can vary its mode of operation to be able to both detect pulse oximetry data and to provide visual images of the fetus. In such embodiments, the pulse oximetry light detecting sensor will have a dual function and the separate imaging device will not be needed.
The spacing mechanisms of the present invention can take a variety of forms. In an exemplary embodiment, the spacing mechanism is an inflatable bladder or balloon that can be positioned between the fetus and distal housing. In one configuration, the inflatable bladder can be filled with a clear medium, such as saline, to provide space between the imaging assembly and the fetus. Because the inflatable bladder and the clear medium are positioned between the fetus and the imaging assembly, bodily fluids such as blood, amniotic fluid, vernix, and mucus are displaced from the field of view of the imaging assembly and do not substantially interfere with the imaging optics. The imaging device allows the physician to continuously monitor the sensor placement site during initial placement of the sensor. As an additional benefit, the imaging device can be used to monitor the position and orientation of the fetus during labor and delivery.
In one aspect, the present invention provides a probe for viewing a fetus. The probe comprises an imaging assembly positioned on a body. A spacing mechanism is disposed on the body to create a space between the imaging assembly and the fetus and/or the in utero environment. The spacing mechanism provides the space to provide a larger field of view for the imaging assembly. In some methods of use, the spacing mechanism will contact the fetus or the in utero environment. In other methods of use, the spacing mechanism will only displace body fluids, such as amniotic fluids, but will not contact the fetus.
In another aspect, the present invention provides a fetal probe system for monitoring a fetus. The system includes a fetal sensor assembly disposed on the body. An optical imaging assembly is positioned adjacent the fetal sensor assembly to visualize the portion of the fetus adjacent the fetal sensor assembly. An expandable spacing mechanism is positioned between the optical imaging assembly and the fetus to create a space between the optics assembly and the fetus.
In a further aspect, the present invention provides a method of monitoring a fetus. The method comprises placing a probe adjacent the fetus. A space is created between the fetus and the probe, and the fetus is imaged with an imaging assembly. An image of a portion of the fetus and/or the in utero environment is transmitted to a viewing display so as to provide a visual indication of the position of the fetus in relation to the fetal probe.
In yet another aspect, the present invention provides a method of displacing body fluids to allow clearer imaging of a target tissue. The method comprises placing a probe adjacent the target tissue. A displacement mechanism is positioned between the target tissue and the probe to displace body fluids (e.g., amniotic fluids, meconium tissue, and the like) so as to provide a field of view for imaging the target tissue. In exemplary methods, the method can be used to image a fetus or in utero environment. It should be appreciated however, that the displacement mechanism can also be used in other non-invasive, minimally invasive, or open surgical procedures.
For a further understanding of the nature and advantages of the invention, reference should be made to the following description taken in conjunction with the accompanying drawings.